Aqueous solutions of fluorescent whitening agents

ABSTRACT

Compositions comprising (A) a total of from 2 to 30% by weight, based on the total composition (A)+(B), of one or more amino alcohols of formula (1) herein R 1 , R 2 , R 3  and R 4  are each independently of the others hydrogen, C 1 -C 12 alkyl, C 5 -C 24 aryl or C 6 -C 36 aralkyl, and R 5  and R 6  are each independently of the other hydrogen or C 1 -C 4 alkyl; and (B) from 70 to 98% by weight, based on the total composition (A)+(B), of a fluorescent whitening agent of formula (2) herein X is hydrogen, an alkali metal ion, an ammonium ion or a hydroxyalkylammonium radical derived from the amino alcohol of formula (1), and R 7 , R 8 , R 9  and R 10  are each independently of the others —OR 11 , —NR 11 R 12  or a group of formula (3) wherein R 11 , and R 12  are each independently of the other hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, dicarboxyalkyl, H 2 N—CO-alkyl or alkylthio, are distinguished by high solubility in water and by high storage stability of the aqueous solutions.

The present invention relates to a composition comprising a sulfo-group-containing fluorescent whitening agent and a β-amino alcohol, to aqueous solutions comprising such a composition and also to the use of the aqueous solutions in the whitening of textile fibres or paper.

Liquid commercial forms of fluorescent whitening agents have the advantage over powders or granules that they are dust-free, can be measured out better and result in a substantial increase in the rate of dissolution in water. However, the solubility of most sulfo-group-containing fluorescent whitening agents in water is insufficient to produce adequately concentrated solutions. In addition, when the aqueous solutions are stored, the fluorescent whitening agents have a tendency to crystallise out. An improvement in solubility and in storage stability is therefore desirable.

It is known that the solubility of fluorescent whitening agents can be increased by adding specific auxiliaries such as urea or ε-caprolactam. However, relatively large amounts of such additives have to be added and then removed subsequently in a laborious waste-water treatment procedure.

It has now been found that the aqueous solubility of sulfo-group-containing fluorescent whitening agents and the storage stability of the aqueous solutions can be substantially improved by the addition of a β-amino alcohol in a relatively small amount.

The present invention relates to a composition comprising

-   -   (A) a total of from 2 to 30% by weight, based on the total         composition (A)+(B), of one or more amino alcohols of formula         (1)     -   wherein R₁, R₂, R₃ and R⁴ are each independently of the others         hydrogen,     -   C₁-C₁₂alkyl, C₅-C₂₄aryl or C₆-C₃₆aralkyl, and R₅ and R₆ are each         independently of the other hydrogen or C₁-C₄alkyl; and     -   (B) from 70 to 98% by weight, based on the total composition         (A)+(B), of a fluorescent whitening agent of formula (2)     -   wherein X is hydrogen, an alkali metal ion, an ammonium ion or a         hydroxyalkyl-ammonium radical derived from an amino alcohol of         formula (1), and R₇, R₈, R₉ and R₁₀ are each independently of         the others —OR₁₁, —NR₁₁R₁₂ or a group of formula     -   wherein R₁₁ and R₁₂ are each independently of the other         hydrogen, alkyl, hydroxy-alkyl, alkoxyalkyl, carboxyalkyl,         dicarboxyalkyl, H₂N—CO-alkyl or alkylthio.

When any radicals in formula (1) or (2) are alkyl, such radicals may be straight-chain or branched radicals. Examples thereof are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, tert-amyl(1,1-dimethylpropyl), 1,1,3,3-tetramethylbutyl, hexyl, 2-methylpentyl, neopentyl, cyclopentyl, cyclohexyl and their respective isomers.

Aryl radicals as substituents R₁ to R₄ have preferably from 5 to 24, especially from 6 to 14, carbon atoms and may be substituted, for example by hydroxy, C₁-C₄alkyl, C₁-C₄alkoxy, C₁-C₄hydroxyalkyl, halogen or by the radical —NH—CO—R, wherein R is amino, C₁-C₄alkyl or unsubstituted or hydroxy-, C₁-C₄alkyl-, C₁-C₄alkoxy-, C₁-C₄hydroxyalkyl- or halo-substituted phenyl.

Examples of suitable aryl groups are phenyl, tolyl, mesityl, isityl, 2-hydroxyphenyl, 4-hydroxyphenyl, 2-chlorophenyl, 4-chlorophenyl, 2,6-dichlorophenyl, 2-aminophenyl, 3-aminophenyl, 4-aminophenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-acetylaminophenyl, naphthyl and phenanthryl.

Aralkyl groups as substituents R₁ to R₄ have preferably from 6 to 36, especially from 7 to 12, carbon atoms and may be unsubstituted or substituted by one or more C₁-C₄alkyl groups, C₁-C₄alkoxy groups, halogen atoms or radicals —NH—CO—R, wherein R is amino, C₁-C₄alkyl or unsubstituted or C₁-C₄alkyl-, C₁-C₄alkoxy- or halo-substituted phenyl.

Examples of suitable aralkyl groups are benzyl, 2-phenylethyl, tolylmethyl, mesitylmethyl and 4-chlorophenylmethyl.

X may be, for example, hydrogen, Na⁺, K⁺, NH₄ ⁺, N(CH₃)₄ ⁺, a di- or tri-alkanolammonium radical, e.g. di- or tri-ethanolammmonium, or a hydroxyalkylammonium radical derived from the amino alcohol of formula (1).

X is preferably hydrogen, Na⁺ or K⁺.

Hydroxyalkyl groups suitable as R₁₁ or R₁₂ are, for example, 4-hydroxy-n-butyl, 3-hydroxy-n-propyl, 2-hydroxy-n-propyl and, especially, 2-hydroxyethyl.

Examples of alkoxyalkyl groups are 2-methoxyethyl and 2-ethoxyethyl.

Carboxyalkyl groups are, for example, 4-carboxy-n-butyl, 3-carboxy-n-propyl, 2-carboxy-n-propyl and, especially, 2-carboxyethyl.

Suitable alkylthio groups are, for example, methylthio, ethylthio and n-propylthio.

Preferred compositions according to the invention comprise, as component (A), 2-amino-2-methyl-1-propanol, 1-amino-2-propanol or a mixture of 2-amino-2-methyl-1-propanol and 2-(N-methylamino)-2-methyl-1-propanol.

As component (B), preference is given to a compound of formula (2) wherein R₇ and R₉ are each a group of formula

wherein R₁₁ is as defined in claim 1.

Preference is furthermore given to compositions according to the invention comprising, as component (B), a compound of formula (2) wherein R₈ and R₁₀ are each —NR₁₁R₁₂ wherein R₁₁ and R₁₂ are each independently of the other hydrogen, 2-hydroxyethyl, 2-carboxyethyl, —CH₂CH₂—CONH₂ or —CH(COOH)—CH₂COOH.

As component (B), special preference is given to compounds of formulae (2a)-(2f)

wherein X is as defined hereinbefore.

Compounds of formula (2) wherein the cation X is derived from an amino alcohol of formula (1) are novel advantageous fluorescent whitening agents in the form of the corresponding hydroxyalkylammonium salts.

The invention accordingly relates also to a compound of formula

wherein X′ is a hydroxyalkylammonium radical derived from an amino alcohol of formula (1) as described hereinbefore and R₇, R₈, R₉ and R₁₀ are as defined herein before.

Special preference is given to compounds of formula (3) wherein the hydroxyalkylammonium radical is derived from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol or a mixture of 2-amino-2-methyl-1-propanol and 2-(N-methylamino)-2-methyl-1-propanol.

Such hydroxyalkylammonium salts are prepared by methods known per se, for example by ion exchange of an alkali metal salt or by treating the free acid with the corresponding amino alcohol (1).

As mentioned hereinbefore, an objective of the invention is to produce aqueous solutions having fluorescent whitening agent concentrations that are as high as possible.

The invention accordingly relates also to an aqueous solution containing

-   -   (A) from 0.5 to 10% by weight of an amino alcohol of formula (1)         according to claim 1 or mixtures thereof,     -   (B) from 5 to 40% by weight of a fluorescent whitening agent of         formula (2) according to claim 1 or mixtures thereof,     -   (C) from 50 to 90% by weight water, and     -   (D) from 0 to 40% by weight of additives,     -   the sum of components (A)+(B)+(C)+(D) being 100% by weight.

The solutions according to the invention may comprise, as optional component (D), various auxiliaries such as, for example, inorganic or organic acids, inorganic salts, urea, non-ionic surfactants, preservatives or water-miscible organic solvents.

Such additives may, depending on the fluorescent whitening agent used, further improve the properties of the solutions; for example, they may increase the maximum fluorescent whitening agent concentration or further reduce the viscosity.

Preferred solutions according to the invention comprise, as component (D), a preservative.

Water-miscible organic solvents such as alcohols, ether alcohols, glycols or carboxylic acid amides may act as solubility promoters.

Examples of such solvents are propanol, isopropanol, ethylene glycol, propylene glycol, glycerol, di- or tri-ethylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, formamide, dimethyl-formamide, dimethylacetamide, ethanolamine, diethanolamine, triethanolamine, N-methyl-pyrrolidone, polyethylene glycols and polyvinylpyrrolidones.

The solutions according to the invention are generally obtained by dissolving the appropriate fluorescent whitening agent or dye in water or a mixture of water and a water-miscible organic solvent with addition of the amino alcohol of formula (1), where appropriate with heating and stirring.

The solutions according to the invention may, depending on the nature of the dissolved fluorescent whitening agent, be used for the whitening of a very wide variety of high molecular weight organic materials. Suitable substrates for whitening are, for example, synthetic, semi-synthetic or natural textile fibres, paper or washing compositions.

The whitening of paper, and also of textiles, may be carried out in the course of surface finishing. For that purpose, the solutions according to the invention are added to the coating compositions required therefor, the latter being understood to be preparations for the coating of paper and other textile and non-textile, natural or synthetic, organic materials, such as, for example, paper coating compositions. Whitening may be accomplished by incorporating solutions according to the invention in the coating compositions to be applied, which are then applied to the substrates in a manner known per se.

Because the solutions according to the invention can be diluted very readily and rapidly with water, they are also excellently suitable for the whitening of textile substrates using conventional fluorescent whitener agent application methods (e.g. the exhaust method or pad thermo method). For that purpose, the concentrated solutions are so diluted with water that the resulting application solutions, to which conventional auxiliaries may also be added, have the desired fluorescent whitening agent concentrations.

Textile fibres suitable for whitening are those of synthetic materials, e.g. polyamide, of semi-synthetic materials, e.g. regenerated cellulose, and also of natural materials, e.g. wool or cotton, as well as fibre blends, e.g. polyester/cotton, it being possible for the natural fibres also to be provided with a finish in a manner customary in the textile industry.

The textile materials to be whitened may be in a variety of processing states (raw materials, semi-finished products or finished products). Fibre materials may be, for example, in the form of staple fibres, flocks, hanks, textile threads, yarns, twisted yarns, non-woven fibre materials, felts, batts, flocked articles, textile composites or knitted articles but are preferably in the form of woven textiles.

Treatment thereof is carried out using the dilute solutions according to the invention, optionally after adding dispersants, stabilisers, wetting agents and further auxiliaries. Depending on the fluorescent whitening agent dissolved, it may be found to be advantageous to carry out the procedure in an acid, alkaline or, preferably, neutral bath. Treatment is usually carried out at temperatures of about from 20 to 140° C., for example at the boiling point of the bath or thereabout (about 90° C.).

The following auxiliaries may also be added to the bath:

dyes (shading), pigments (coloured or, especially, white pigments), carriers, wetting agents, softening agents, swelling agents, antioxidants, light stabilisers, heat stabilisers, chemical bleaching agents, crosslinking agents, finishing agents and also agents used in various textile finishing methods, especially agents for synthetic resin finishes, and also flame retardant, soft handle, dirt release or antistatic finishes or antimicrobial finishes.

Diluting the concentrated fluorescent whitening agent solutions according to the invention to form the corresponding application baths is carried out in such a manner that, when the substrate in question is impregnated, it takes up the fluorescent whitening agent in an amount of at least 0.0001% by weight, but at most 2% by weight, preferably from 0.0005 to 0.5% by weight. The required concentration is derived by simple means from those values depending on the liquor ratio to be used, the nature of the substrate and the fluorescent whitening agent dissolved.

The solutions according to the invention may also be added to washing baths or to washing compositions. To washing baths there is simply added an amount of solution that contains the desired amount of fluorescent whitening agent. The solutions according to the invention may be added to washing compositions in any phase of the production process, for example to the slurry before atomisation of the washing powder or during preparation of liquid washing agent combinations.

The Examples that follow illustrate the invention:

The solutions described in Examples 1, 2 and 3 are produced by mixing the individual components and are subjected to a storage stability and temperature stability test.

The results are compiled in Table 1.

EXAMPLE 1

22% by weight compound of formula (2b) wherein X is H

5% by weight 1-amino-2-propanol

73% by weight deionised water

EXAMPLE 2

22% by weight compound of formula (2b) wherein X is H

5% by weight 2-amino-2-methyl-1-propanol

73% by weight deionised water

EXAMPLE 3

19.9% by weight compound of formula (2b) wherein X is H

2.5% by weight 2-amino-2-methyl-1-propanol

2.0% by weight KOH (50%)

75.6% by weight deionised water TABLE 1 Storage stability test at different temperatures Ex. Temp. 1 day 1 week 2 weeks 1 month 1 −5° C. sample frozen  0° C. O.K. O.K. O.K. O.K. RT O.K. O.K. O.K. O.K. 40° C. O.K. O.K. O.K. O.K. 60° C. O.K. O.K. O.K. O.K. 2 −5° C. sample frozen  0° C. O.K. O.K. O.K. O.K. RT O.K. O.K. O.K. O.K. 40° C. O.K. O.K. O.K. O.K. 60° C. O.K. O.K. O.K. O.K. 3 −5° C. O.K. sample frozen sample frozen  0° C. O.K. trace of crystal trace of crystal trace of crystal formation on boiling formation on boiling formation on boiling chips chips chips RT O.K. O.K. O.K. O.K. 40° C. O.K. O.K. O.K. O.K. 60° C. O.K. O.K. O.K. O.K. RT = room temperature

TABLE 2 Temperature ramp Ex. 0° C. −2° C. −4° C. −6° C. −8° C. −10° C. 1 O.K. O.K. O.K. O.K. O.K. frozen 2 O.K. O.K. O.K. frozen 3 O.K. O.K. O.K. O.K. reversibly frozen

TABLE 3 5 freeze/thaw cycles Example 1 2 3 O.K. O.K. O.K. 

1. A composition comprising: (A) a total of from 2 to 30% by weight, based on the total composition (A)+(B), of one or more amino alcohols of formula (1)

wherein R₁, R₂, R₃ and R₄ are each independently of the others hydrogen, C₁-C₁₂alkyl, C₅-C₂₄aryl or C₆-C₃₆aralkyl, and R₅ and R₆ are each independently of the other hydrogen or C₁-C₄alkyl; and (B) from 70 to 98% by weight, based on the total composition (A)+(B), of a fluorescent whitening agent of formula (2)

wherein X is hydrogen, an alkali metal ion, an ammonium ion or a hydroxyalkylammonium radical derived from an amino alcohol of formula (1), and R₇, R₈, R₉ and R₁₀ are each independently of the others —OR₁₁, —NR₁₁R₁₂ or a group of formula

wherein R₁₁, and R₁₂ are each independently of the other hydrogen, alkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, dicarboxyalkyl, H₂N—CO-alkyl or alkylthio.
 2. A composition according to claim 1, comprising, as component (A), 2-amino-2-methyl-1-propanol, 1-amino-2-propanol or a mixture of 2-amino-2-methyl-1-propanol and 2-(N-methylamino)-2-methyl-1-propanol.
 3. A composition according to claim 1, comprising, as component (B), a compound of formula (2) wherein R₇ and R₉ are each a group of formula

wherein R₁₁ is as defined in claim
 1. 4. A composition according to claim 1, comprising, as component (B), a compound of formula (2) wherein R₈ and R₁₀ are each —NR₁₁R₁₂ wherein R₁₁ and R₁₂ are each independently of the other hydrogen, 2-hydroxyethyl, 2-carboxyethyl, —CH₂CH₂—CONH₂ or —CH(COOH)—CH₂COOH.
 5. A composition according to claim 1, comprising, as component (B), a compound of formula (2a)-(2f)

wherein X is as defined in claim
 1. 6. A compound of formula

wherein X′ is a hydroxyalkylammonium radical derived from an amino alcohol of formula (1) according to claim 1 and R₇, R₈, R₉ and R₁₀ are as defined in claim
 1. 7. A compound of formula (3) according to claim 6, wherein the hydroxyalkylammonium radical is derived from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol or a mixture of 2-amino-2-methyl-1-propanol and 2-(N-methylamino)-2-methyl-1-propanol.
 8. An aqueous solution containing (A) from 0.5 to 10% by weight of an amino alcohol of formula (1) according to claim 1 or mixtures thereof, (B) from 5 to 40% by weight of a fluorescent whitening agent of formula (2) according to claim 1 or mixtures thereof, (C) from 50 to 90% by weight water, and (D) from 0 to 40% by weight additives, the sum of components (A)+(B)+(C)+(D) being 100% by weight.
 9. An aqueous solution according to claim 8, comprising, as component (D), a preservative.
 10. A method of whitening of natural, semi-synthetic or synthetic textile fibres, which comprises contacting said fibres with an effective whitening amount of an aqueous solution according to claim
 8. 11. A method of whitening paper, which comprises contacting said paper with an effective whitening amount of an aqueous solution according to claim
 8. 